LeetCode 1207. Unique Number of Occurrences

Problem Statement

impl Solution {
    pub fn unique_occurrences(arr: Vec<i32>) -> bool {
        use std::collections::{HashMap, HashSet};

        let (mut map, mut set) = (HashMap::new(), HashSet::new());
        for i in arr {
            *(map.entry(i).or_insert(0)) += 1;
        }

        for (_, val) in map {
            if set.contains(&val) {
                return false;
            }
            set.insert(val);
        }
        return true;
    }
}